Accurate prediction of coke yield is the basis for simulation and operation of the in situ combustion process. In view of the low asphaltene content of heavy oil in China, this study established coke yield prediction models for the pyrolysis and oxidation processes of low-asphaltene heavy oil based on the coking characteristics of the main fractions, including saturates (S), aromatics (A), and resins (R). The models were verified by the experimental coke yields of heavy oils using a fixed-bed reaction system. The prediction model for the pyrolysis process included evaporation rate equations and kinetic equations for coking reactions. Besides the same parts with pyrolysis, the model for the oxidation process included the kinetic equation of coke oxidation. The evaporation rate equations were determined by fitting the mass loss rate in the evaporation range of thermogravimetric analysis (TGA) pyrolysis results with a maximum error of 6%. The kinetic parameters for the conversion of each fraction to the coke precursor were determined by the isoconversional method based on TGA results of the separated SAR fractions. Considering the interactions among fractions during oxidation, this study included mixtures of SAR fractions as the samples and obtained the mass loss results of a single SAR by subtraction. The activation energies of SAR pyrolysis range from 99 to 180 kJ/mol and those of SAR oxidation range from 92 to 130 kJ/mol. The kinetic parameters of coke from the coke precursor were obtained by temperature-programmed coking data of a prepared intermediate, with an activation energy of 177 kJ/mol in an inert atmosphere and 65 kJ/mol in an oxidizing atmosphere. The kinetic parameters of coke oxidation were derived by the isothermal kinetic method in TGA, with an activation energy of 136 kJ/mol. The experimental coke yields of Fengcheng and Hongqian heavy oils under various pyrolysis and oxidation conditions were predicted by this model with an error around 10%, indicating that this model could be successfully applied to the prediction of the coking process of low-asphaltene heavy oil under complex conditions.

Abstract. With the speeding up of urbanization process, ecological problems, such as unsustainable land use and environmental pollution,have emerged one after another in cites. Nowadays, green development and ecological priority are the important concepts and trends of the current new urban planning in China. In this study, Pingtan County, a coastal city in Fujian Province, China, was taken as the research area. Based on two Landsat 8 remote sensing images (2016, 2017), and two Sentinel-2A remote sensing images (2016, 2017), we first adopt the modified normalized water body index (MNDWI) to mask the water body. Four indicators, including greenness, humidity, dryness and heat were extracted to synthesize the remote sensing ecological index (RSEI), which were obtained by principal component analysis method. Based on the RSEI values acquired from Landsat 8 and Sentinel-2A images, the ecological environment change trend in Pingtan County was evaluated .The experimental results show that: 1) The RSEI indicators based on Landsat 8 and sentinel data all show a downward trend, but due to due to the influence of image spatial resolution and PCA weighting coefficient, the RSEI index has different degrees of decline. 2) The main reason for the decline in RSEI is the increase in NDSI indicators. Compared with July 2016, the bare ground increased in April 2017. Although the NDVI has increased, the overall trend is still declining. Therefore, it is necessary to ecologically return farmland and improve vegetation coverage in the future development process. 3) In recent years, the ecological quality of new construction land near drinking water sources has declined, so it is necessary to strengthen monitoring of changes in the region.

Scale effect is a crucial scientific problem in quantitative remote sensing (RS), and scholars attempt to solve it with scale conversion models, which can characterize the numerical relationship of RS land surface parameters at different resolutions (scales). As a significant land surface parameter, scale conversion of normalized difference vegetation index (NDVI) has been studied for a long time. Therefore, taking NDVI as an example, the development of scaling research is described and analyzed in the paper, and based on fractal theory, the development trends are discussed for land surface parameters in quantitative remote sensing. These are our conclusions: it will be the new trend to establish downscaling models based on fractal theory for land surface parameters in quantitative remote sensing; additionally, it still is the hotspot to establish spatiotemporal scale conversion models for land surface parameters in quantitative remote sensing in the future, and addressed on that, the multi-fractal scaling methodology is proposed, and its availability is analyzed in the paper, which presents significant potential.

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Rapid urbanization has placed the sustainable development of some watershed ecosystems in jeopardy. In order to achieve sustainable urban development, it is vital to identify the coupling mechanisms between urbanization and the ecological environment quality. This study establishes indicators to evaluate the Jiulong River Basin’s urbanization and ecological environment systems. These are utilized to analyze spatial and temporal changes and build a coupling coordination degree model. This research investigates the level of development coordination between urbanization and the ecological environment quality in the basin. The data sources include nighttime lighting and Landsat data from 2000 to 2020. The findings indicated the following: 1) Urbanization levels in the basin rise annually, and the years 2010–2020 represent a stage of high urbanization growth. In addition, the development levels are spatially heterogeneous, with high levels in the south and low levels in the north. 2) The ecological environment quality category for the basin is generally Excellent; however, many facets of the climate and human activity drastically lowered this grade in 2005. 3) In the basin, there is a basic coordination relationship between urbanization and environmental quality, but the number of cities falling into the moderate imbalance category has grown. 4) Increasing the urbanization level raises the coordination between urbanization and the ecological environment more than improving environmental quality, but antagonistic effects make it necessary to strengthen the protection of the ecological environment alongside economic development. From the viewpoint of counties, this study examines the long-term interactions between the ecological environment and urbanization in Fujian Province, China. Recommendations for balancing urban development and environmental concerns in coastal watersheds are presented, providing references to the fact that the future of this area of China can be sustainable.